RICK FERRI: Back in 1982, when I was a young 2nd Lieutenant in the Marine Corps, I made a $2,000 investment in a popular U.S. stock mutual fund. I checked the charts, listened to the gurus, and became convinced that the market was poised to head higher. Stock prices fell another 10% almost immediately. I sold the fund. That’s when the stock market began its 18-year bull run.

Trying to time when to buy was my first mistake; getting out was my second. Moral of the story: Don’t try to time the market.

Rick Ferri is founder of Portfolio Solutions LLC and the author of books on low-cost index fund and ETF investing. His blog is RickFerri.com.